Hair drug testing: Many street drugs (or their breakdown products in the body) are absorbed into the hair. A sample of hair can be tested for recent drug use. Hair analysis: Testing of hair for toxic exposures, such as lead or mercury poisoning.
Gas Water Heater, water not hot enough-Thermostat or Sediment. The dip tube probably disintigrated. The dip tub sends cold water to the bottom of the tank for heating when its heated it rises to the top of the tank. Its possible that the dip tube broke of and now you have cold water mixing with the hot water on top.
Photo: A thermostatically controlled gas valve. Pressure relief vs. Temperature Pressure Relief The two contributing factors that cause water heaters to explode are excessive water temperature and a failing in the tank itself. The failing or weakness could be in the design or could be caused by a defect from extensive corrosion or just normal wear.